The present invention relates to an improvement of a fuel filter incorporated in a fuel tank, the fuel filter having a suction passage penetrating an end of a meshed body of a bag shape and open to the inside of the meshed body and a swollen supporter at the inside thereof.
A gravity of a fuel such as gasoline, etc. used in automobiles is lighter than that of water. Hence, if water once enters into the fuel tank, the water is accumulated at the bottom of the fuel tank separated from the fuel. Once the water is accumulated in the fuel tank, it is not discharged outside for thereby increasing the amount of accumulated water.
Meanwhile, inasmuch as a suction pipe for drawing the fuel from the fuel tank is required to draw as much fuel as possible and to reduce the fuel level in the fuel tank as low as possible, it is advisable to position an opening of the suction pipe near the bottom of the fuel tank as close as possible. If the opening of the suction pipe is very close to the bottom of the fuel tank, the water accumulated in the bottom of the fuel tank is liable to be drawn from the opening of the suction pipe. Hence, there is provided a fuel filter formed in a meshed body and attached to a tip end of the suction pipe for preventing the water from being drawn from the fuel tank but allowing only the fuel to be drawn from the fuel tank and allowing impurities in the fuel tank to be filtered.
A liquid has a surface tension peculiar thereto. Since the meshed body has a plurality of perforations, a resistance generated when the liquid passes the perforations is varied depending on the surface tension peculiar to the liquid. For example, as far as the resistance of the liquid is concerned when the water and the fuel pass the perforations, the resistance of water is greater than that of the fuel. Hence, at the time when the meshed body is soaked both in the water and the fuel, the suction pipe draws the fuel only. The present fuel filter incorporated in the fuel tank has been made to utilize this phenomenon.
A prior art fuel filter incorporated in a fuel tank of automobiles will be described with reference to FIG. 19.
A fuel filter unit U comprises a suction member 1, a meshed baggy body 2 and a swollen supporter 3 for keeping a swollen state of the meshed baggy body 2. The suction member 1 comprises an end member 1A to be pressed and fitted in the end portion of a suction pipe P and a fastening member 1B for clamping and fastening a meshed body described later. The meshed baggy body 2 is composed of one meshed body 2A and another meshed body 2B, and the end member 1A penetrates the portion adjacent to the center of the one meshed body 2A. The meshed bodies 2A and 2B are respectively circular or tetragon according to the present invention and the circumferences or four sides thereof are welded (M). The swollen supporter 3 is housed inside the meshed baggy body 2 for keeping the swollen state of the meshed baggy body 2.
However there are the following drawbacks in the prior art fuel filter. Firstly, inasmuch as the suction member 1 penetrates the central portion of the tetragon or circular meshed baggy body 2, an interval H is spaced between the suction pipe P and the periphery of the fuel filter unit U. Even if the suction pipe P is preferably positioned adjacent to a wall of the fuel tank T as close as possible, the suction pipe P must nevertheless be spaced apart from the fuel tank T by the interval H. Accordingly, with the arrangement of the prior art filter, the suction pipe P has to be installed in the fuel tank T with a restricted degree of freedom of installation. When the meshed baggy body 2 is formed, the one meshed body 2A is laid over the other meshed body 2B, and the circumferences thereof 2A, 2B are welded. It took time and labor for welding the circumferences of both meshed bodies 2A, 2B.
Secondly, inasmuch as the fuel filter unit U incorporated in the fuel tank is installed adjacent to the bottom wall of the fuel tank T, there is a likelihood of breakage due to rubbing and abrasion between the bottom wall of the fuel tank and the meshed body 2B upon the occurrence of vibration.
Thirdly, when the fuel is drawn, a pulsation motion is generated in the drawn fuel which affects unfavorably the supply of fuel.